The present invention relates to an improved spring-actuated parking brake for vehicles equipped with power-operated (non-muscular energy) braking systems.
Parking braking systems for vehicles are available in diverse types, including cable parking brakes, air-released spring-actuated parking brakes and hydraulically releasable spring-actuated parking brakes. A complex cable mechanism is a primary disadvantage of cable parking brakes, as it takes up considerable space and is highly susceptible to malfunction. Also, automatic brake actuation is not possible with cable parking brakes. Disadvantages of conventional air-released spring-actuated parking brakes lie mainly in the complex compressed air supply and in the requirement to locate the operating valve for the spring-actuated brake in the vehicle cab. Disadvantages of conventional hydraulically releasable spring-actuated brakes lie mainly in the complex valves and hydraulic pressure supply and the location of pressure lines in the vehicle cab.
It is desired to provide an improved spring-actuated vehicle parking brake that overcomes the disadvantages associated with conventional constructions and that avoids undesired changes in the condition of the parking brake due to improper driver operation or occurrence of failures, while satisfying legal requirements applicable to such vehicle parking brakes.